OPQR is a horizontal plane rectangle of negigible mass. Its side lengths are OP =RQ =2m and OR = PQ = 1m. Forces act along each side of the rectangle.

If OP is taken to be i direction and j to be the direction of OR. The force K is given by -40i. If the rectangle is in equilibrium what is the force acting along PQ?

I think the answer is 20J- anyone help?